The present invention relates to an annular element for a rolling bearing, of the type comprising a cylindrical surface in which a groove having a radial depth which is variable around the circumference of the cylindrical surface is formed, the surface being suitable for being over-moulded with a plastics material to form a body which is fixed for rotation with the annular element and has a plastics projection complementary with the groove and suitable for cooperating with the groove to prevent relative rotation between the annular element and the plastics body.
Annular elements of the above-mentioned type are known, for example, from EP-A-0 972 958, U.S. Pat. No. 3,832,024, and U.S. Pat. No. 4,925,322. These publications describe bearings having rings which have eccentric grooves with rectangular axial sections.
A disadvantage which arises when a plastics body is moulded over an annular element of a rolling bearing is due to the fact that, because of the different coefficients of thermal expansion of steel and plastics, the plastics body tends to rotate slowly relative to the ring of the bearing; this phenomenon is known by the term xe2x80x9ccreepingxe2x80x9d. The relative rotation between the plastics and the steel of the bearing causes rapid wear of the plastics due to friction so that the assembly becomes noisy and is inevitably subject to excessive vibrations and breakage.
A general object of the present invention is to provide an annular element of the above-mentioned type which more effectively prevents relative rotation between the annular element and the plastics body moulded over it.
A particular object of the invention is to provide an annular element for a rolling bearing which is suitable for supporting a rotating shaft of a drum in a washing machine without incurring the problems mentioned above, and which is specifically adapted to prevent the vibrations caused by the rotation of the drum from reaching unacceptable values.
These objects are achieved, according to the present invention, by an annular element.